Formulations for high selective silicon nitride etch

ABSTRACT

Compositions useful for the selective removal of silicon nitride materials relative to polysilicon, silicon oxide materials and/or silicide materials from a microelectronic device having same thereon are provided. The compositions of the invention are particularly useful in the etching of 3D NAND structures.

FIELD OF THE INVENTION

The present invention relates to a composition and method forselectively etching silicon nitride in the presence of silicon oxide,polysilicon and/or metal silicides, and more particularly to acomposition and method for effectively and efficiently etching a layerof silicon nitride at a high etch rate and with high selectivity withrespect to exposed or underlying layers of silicon oxide, polysiliconand/or metal silicides, particularly in a multilayer semiconductor waferstructure.

BACKGROUND OF THE INVENTION

With the continued demand for improved microelectronic deviceperformance there is a continued emphasis on decreasing devicedimensions, which provides the dual advantages of dramaticallyincreasing device density as well as improving device performance.Device performance is improved because decreased device dimensionsresult in shorter paths that need to be traveled by charge carriers,e.g., electrons.

For example, Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFET)gate electrodes have as electrical points of contact the gate surfaceand the source and drain regions. The distance between the source anddrain regions forms the channel length of the gate electrode, and assuch, by decreasing device dimensions the channel length isconcomitantly decreased. The result is that the switching speed of thedevice is increased.

It is self-evident that reducing device dimensions results in increasedpackaging density of devices on a microelectronic device chip. Thisincreased packaging density brings with it sharp reductions in thelength of the interconnect paths between devices, which reduces therelative negative impact (such as resistive voltage drop, cross talk orRC delay) that these interconnect paths have on overall deviceperformance.

Such requirements however cause problems of increased parasiticcapacitance, device contact resistance (gate, source and drain contactsin MOSFET devices), and tight tolerance of pattern definition. For verysmall sub-micron or sub-half-micron or even sub-quarter-micron modernsilicon devices, the conventional photolithographic technique forpatterning contacts will not meet the required tolerance of criticaldimensions. Methods that have been explored to improve resolution andfeature size include the formation of a self-aligned poly-silicon(poly-Si) gate structure, which helps to solve the problem of criticaldimension tolerance. Using this method, the contact points that areformed for the source and the drain of the gate electrode self-alignwith the poly-Si gate.

One problem encountered during the formation of self-aligned gatestructures has been the selective removal of silicon nitride materialsrelative to polysilicon, silicon oxide and/or metal silicide materials.For example, during the anisotropic etching of the silicon nitride layercovering the gate electrodes, the underlying silicon oxide layer andsilicon substrate are often damaged as well, causing a deterioratedreliability of a semiconductor device.

Conventional wet etching techniques for selectively removing siliconnitride (Si₃N₄) have utilized hot (approximately 145-180° C.) phosphoricacid (H₃PO₄) solutions with water, typically 85% phosphoric acid and 15%water (by volume). Using fresh hot phosphoric acid, the typicalSi₃N₄:SiO₂ selectivity is about 40:1. Advantageously, as the nitridelayer is removed, hydrated silicon oxide forms, which consistent with LeChatelier's principle, inhibits the additional removal of silicon oxidefrom the device surface; thus selectivity gradually increases with use.Disadvantages associated with the use of hot phosphoric acid etchesinclude the corrosion of metal silicide materials, e.g., gate contactmaterials, the etching of silicon oxide, and process control due to thedifficultly associated with maintaining a specific amount of water inthe process solution. In addition, hot phosphoric acid has been adifficult medium to adapt to single wafer tools, which have becomeincreasingly preferred by many manufacturers.

Another way to selectively remove silicon nitride includes the use of acomposition including hydrofluoric acid, however, said compositions alsoremove silicon oxides. A Si₃N₄:SiO₂ selectivity of about 10:1 can beachieved through dilution; however, the etch rate of silicon nitride iscompromised or above-ambient pressure must be used. Still anotherprocess to remove silicon nitride includes the dry etch removal usinghalogenated gaseous species; however, the Si₃N₄:SiO₂ selectivity ratiois even worse than that obtained using the aforementioned wet etchprocesses.

3D-NAND structures in development today at all the major memory chipmanufacturers require high-selectivity etching of silicon nitride (SiN)out of high aspect ratio “slits” defined by oxide (PETEOS). In theregular hot phosphoric acid “hot phos” process the selectivity iscontrolled by pre-dissolving a certain amount of nitride. The dissolvedsilicon nitride is converted into slightly soluble oxide; the samehappens during etching, but the oxide soon starts depositing near theslits' openings, eventually blocking them. See also US 2017/0287725, inparticular FIG. 1D, which shows an illustration where the deposition ofcolloidal silica tends to “pinch off” the gaps or trenches in themicroelectronic device. As a result, the process window of pre-etchoxide concentration is very narrow, difficult to control, and the etchbath has to be replaced very often. Oxide re-deposition rate thus needsto be minimized.

In addition, the deep slits take a long time to etch (typically >1hour). Addition of HF in small amounts increases etch rates, but alsopolymerization of soluble silica species and consequently oxidere-deposition rates. Furthermore, the volatility of HF and relatedfluorinated species causes process control difficulties.

In planar NAND technology, scaling is driven mostly by lithography. Inscaling 3D NAND, extreme precision and process repeatability is requiredto create complex 3D structures with very high-aspect-ratio (HAR)features. Therefore, achieving success with 3D NAND requires innovativepatterning solutions that minimize variability. (See OvercomingChallenges in 3D NAND Volume Manufacturing. Solid State Technologywebsite:http://electroig.com/blog/2017/07/overcoming-challenges-in-3d-nand-volume-manufacturing/)

Precision in etching extreme HAR features is critical for optimizingchannel holes and trenches for cell access, as well as its uniquestaircase structure architecture, which connects the cells tosurrounding CMOS circuitry for reading, writing, and erasing data. Ifthe vertical pitch of the memory stack is around 50 nm, then a 96 layerstack is on the order of 4.8 μm high. This corresponds to a challengingaspect ratio of ˜100:1.

Additionally, as multilayer stack heights increase, so does thedifficulty in achieving consistent etch and deposition profiles at thetop and the bottom of the memory array. For example, given a ratio of˜100:1, the selective removal of Si₃N₄ in the memory stack becomes awet-etch challenge. The difficulty is removing the Si₃N₄ consistently atthe top and the bottom of the stack and across the wafer, withoutetching any of the SiO₂. Below 96 layers, this task is performed usinghot phosphoric acid (˜160° C.); however, at 96 layers and above, aspecially formulated wet etch chemistry is needed to improve processmargin.

SUMMARY OF THE INVENTION

In one aspect, the invention provides compositions useful in etching asubstrate having a surface comprising silicon nitride and silicon oxide,with selectivity for etching the silicon nitride relative to the siliconoxide. The composition comprises phosphoric acid, at least one compoundchosen from tetraalkyldisiloxane-silyldiamines;

linear and cyclic alkylsilazanes,

1,2 bis(n-aminoalkoxy) tetraalkylsiloxanes,

alkyl, aryl, alkenyl, heteroalkyl/aryl boronic acids,

tungstosilicic acid,

phosphotungstic acid,

poly(vinyl alcohol),

poly(vinylpyrrolidone),

O-phosphorylethanolamine,

phosphorylcholine,

phosphatidylserine

trialkylsilylamines,

trialkylsilylurea, and

trialkylsilylcarbamates.

a solvent comprising water, and optionally a fluoride compound.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the selectivity variation for two etch formulations ondifferent types of oxide and nitride substrates with different surfacechemistry, made by different deposition techniques. Etch rate inangstroms per minute on the substrates listed is plotted comparing (i)85% phosphoric acid and (ii) 85% phosphoric acid combined with 0.0002moles of (3-aminopropyl)silane triol.

DETAILED DESCRIPTION OF THE INVENTION

One aspect of the present invention relates to compositions which areuseful in the selective removal of silicon nitride relative topolysilicon (poly-Si) and silicon oxide material deposited from asilicon oxide precursor source, and hence are useful as wet etchants forat least partial removal of silicon nitride material from amicroelectronic device. Metal silicide materials that may be presentshould not be substantially corroded by said removal compositions.

The invention also provides methods, processes, and systems for usingthe wet etching compositions to remove silicon nitride from a substratecontaining silicon nitride and silicon oxide. The compositions canproduce an advantageously high etch rate of silicon nitride, anadvantageously high selectivity of silicon nitride relative to siliconoxide, or an advantageous balance of these performance properties.

For ease of reference, “microelectronic device” corresponds tosemiconductor substrates, including 3D NAND structures, flat paneldisplays, and microelectromechanical systems (MEMS), manufactured foruse in microelectronic, integrated circuit, or computer chipapplications. It is to be understood that the term “microelectronicdevice” is not meant to be limiting in any way and includes anysubstrate that includes a negative channel metal oxide semiconductor(nMOS) and/or a positive channel metal oxide semiconductor (pMOS)transistor and will eventually become a microelectronic device ormicroelectronic assembly.

As used herein, “suitability” for removing silicon nitride material froma microelectronic device having such nitride material thereoncorresponds to at least partial removal of silicon nitride material fromthe microelectronic device.

As used herein, “silicon nitride” and “Si₃N₄” correspond to pure siliconnitride (Si₃N₄) as well as impure silicon nitride including hydrogen,carbon and/or oxygen impurities in the crystal structure.

As used herein, “silicon oxide” refers to thin films made of siliconoxide (SiOx), e.g., SiO₂, “thermal oxide” (ThOx), and the like. Thesilicon oxide can be placed on the substrate by any method, such as bydeposition via chemical vapor deposition from TEOS or another source, orby being thermally deposited. The silicon oxide generally contains acommercially useful low level of other materials or impurities. Thesilicon oxide may be present as part of a microelectronic devicesubstrate as a feature of the microelectronic device, for example as aninsulating layer.

As used herein, “at least partial removal of silicon nitride material”corresponds to the removal of at least a portion of the exposed siliconnitride layer. For example, partial removal of silicon nitride materialincludes the anisotropic removal of a silicon nitride layer thatcovers/protects the gate electrodes to form a Si₃N₄ sidewall. It is alsocontemplated herein that the compositions of the present invention maybe used more generally to substantially remove silicon nitride materialrelative to poly-silicon and/or silicon oxide layers. In thosecircumstances, “substantial removal” is defined in one embodiment as atleast 90%, in another embodiment at least 95%, and in yet anotherembodiment at least 99% of the silicon nitride material is removed usingthe compositions of the invention.

As used herein, “about” is intended to correspond to +/−5% of the statedvalue.

As used herein, “metal silicide” corresponds to any silicide includingthe species Ni, Pt, Co, Ta, Mo, W, and Ti, including but not limited toTiSi₂, NiSi, CoSi₂, NiPtSi, tantalum silicide, molybdenum silicide, andtungsten silicide.

“Silicic acid” is a general name for a family of chemical compounds ofsilicon, hydrogen, and oxygen, with the general formula[SiO_(x)(OH)_(4-2x)]_(n), and includes the compounds metasilicic acid((H₂SiO₃)_(n)), orthosilicic acid (H₄SiO₄), disilicic acid (H₂Si₂O₅),and pyrosilicic acid (H₆Si₂O₇). Silicic acid can be obtained in manyways well known to those skilled in the art, e.g. by hydrating finesilica powder (preferably 1 μm diameter or less), alkoxysilanes (e.g.,tetramethoxysilane (TMOS), tetraethoxysilane (TEOS),tetra-n-propoxysilane, tetra-n-butoxysilane), alkoxysilanes with aminogroups (e.g., aminotriethoxysilane, hexaethoxydisilazane), alkoxysilaneswith one or more halogen pseudohalogen groups (e.g.,triethoxychlorosilane, triethoxyfluorosilane,triethoxy(isocyanato)silane, diethoxydichlorosilane), or combinationsthereof. For ease of reference, “alkoxysilane” will hereinafter be usedto include alkoxysilanes, alkoxysilanes with amino groups andalkoxysilanes with one or more halogen or pseudohalogen groups.

As described herein, the silicon oxide layer may be deposited from asilicon oxide precursor source, e.g., TEOS, or may be thermallydeposited silicon oxide. Other typical low-κ materials “low-k dielectricmaterial” corresponds to any material used as a dielectric material in alayered microelectronic device, wherein the material has a dielectricconstant less than about 3.5. In certain embodiments, the low-κdielectric materials include low-polarity materials such assilicon-containing organic polymers, silicon-containing hybridorganic/inorganic materials, organosilicate glass (OSG), TEOS,fluorinated silicate glass (FSG), silicon dioxide, silicon oxycarbide,silicon oxynitride, silicon nitride, carbon-doped oxide (CDO) orcarbon-doped glass, for example, CORAL™ from Novellus Systems, Inc.,BLACK DIAMOND™ from Applied Materials, Inc. (e.g., BD1, BD2, and BD3designations for PECVD) SiLK™ dielectric resins from Dow (polymers basedon crosslinked polyphenylenes by reaction of polyfunctionalcyclopentadienone and acetylene-containing materials; see, for example,U.S. Pat. No. 5,965,679, incorporated herein by reference), andNANOGLASS™ of Nanopore, Inc, (Silica aerogel/xerogel (known asnanoporous silica), and the like. It is to be appreciated that the low-κdielectric materials may have varying densities and varying porosities.

The compositions of the present invention must possess good metalcompatibility, e.g., a low etch rate on the interconnect metal and/orinterconnector metal silicide material. Metals of interest include, butare not limited to, copper, tungsten, cobalt, molybdenum, aluminum,tantalum, titanium and ruthenium.

Silicides of interest include any silicide including the species Ni, Pt,Co, Ta, Mo, W, and Ti, including but not limited to TiSi₂, NiSi, CoSi₂,NiPtSi, tantalum silicide, molybdenum silicide, and tungsten silicide.

Compositions of the invention may be embodied in a wide variety ofspecific formulations, as hereinafter more fully described.

In all such compositions, wherein specific components of the compositionare discussed in reference to weight percentage ranges including a zerolower limit, it will be understood that such components may be presentor absent in various specific embodiments of the composition, and thatin instances where such components are present, they may be present atconcentrations as low as 0.001 weight percent, based on the total weightof the composition in which such components are employed.

The composition includes aqueous phosphoric acid (e.g., concentratedphosphoric acid) in an amount that is effective to produce desiredetching of silicon nitride. The term “aqueous phosphoric acid” refers toan ingredient of the composition that is mixed or combined with otheringredients of the composition to form the composition. The term“phosphoric acid solids” refers to the non-aqueous component of anaqueous phosphoric acid ingredient, or of a composition that is preparedfrom aqueous phosphoric acid ingredient.

The amount of phosphoric acid solids contained in a composition can bean amount that, in combination with the other materials of an etchingcomposition, will provide desired etching performance, including desiredsilicon nitride etch rate and selectivity, which typically requires arelatively high amount (concentration) of phosphoric acid solids. Forexample, an etching composition can contain an amount of phosphoric acidsolids that is at least about 50 weight percent based on total weight ofthe composition, e.g., at least 70, or at least about 80 or 85 weightpercent phosphoric acid solids based on total weight of the composition.

To provide a desired amount of phosphoric acid solids, the compositionmay contain “concentrated” phosphoric acid as an ingredient that ismixed or combined with other ingredients (one ingredient optionallybeing water, in some form) to produce the composition. “Concentrated”phosphoric acid refers to an aqueous phosphoric acid ingredient thatcontains a high or maximum amount of phosphoric acid solids in thepresence of a low or minimum amount of water and substantially no otheringredients (e.g., less than 0.5 or 0.1 weight percent of any non-wateror non-phosphoric acid solids materials). Concentrated phosphoric acidcan typically be considered to have at least about 80 or 85 weightpercent phosphoric acid solids in about 15 or 20 weight percent water.Alternately, the composition may be considered to include an amount ofconcentrated phosphoric acid that is diluted with water, meaning forexample concentrated phosphoric acid that has been diluted with anamount of water before or after being combined with other ingredients ofthe etching composition, or an equivalent formed in any manner. Asanother alternative, an ingredient of the composition can beconcentrated phosphoric acid or a diluted phosphoric acid, and theetching composition can contain an additional amount of water that isprovided to the composition either as a component of a differentingredient or as a separate water ingredient.

As an example, if concentrated phosphoric acid is used to form thecomposition, the amount of concentrated phosphoric acid (85 weightpercent, in water) can be an amount that is at least 60, e.g., at least80 or at least 90, 93, 95, or at least 98 weight percent of thecomposition, based on total weight of the composition.

The compositions can comprise, consist of, or consist essentially of therecited ingredients and any combination of optional ingredients. As ageneral convention throughout the present description, the compositionas described, or an ingredient or component thereof, that is said to“consist essentially of” a group of specified ingredients or materialsrefers to a composition that contains the specified ingredients ormaterials with not more than a low or insignificant amount of otheringredients or materials, e.g., not more than 5, 2, 1, 0.5, 0.1, or 0.05parts by weight of other ingredients or materials. For example, acomposition that contains materials that consist essentially of: aqueousphosphoric acid, at least one compound chosen from:tetraalkyldisiloxane-silyldiamines;

linear and cyclic alkylsilazanes,

1,2 bis(n-aminoalkoxy) tetraalkylsiloxanes,

alkyl, aryl, alkenyl, heteroalkyl/aryl boronic acids,

tungstosilicic acid,

phosphotungstic acid,

poly(vinyl alcohol)l,

poly(vinylpyrrolidone),

O-phosphorylethanolamine,

phosphorylcholine,

phosphatidylserine

trialkylsilylamines,

trialkylsilylurea, and

trialkylsilylcarbamates, and a solvent comprising water, and optionalingredients as described herein, means a composition that contains theseingredients and not more than 5, 2, 1, 0.5, 0.1, or 0.05 parts by weightof any other dissolved or un-dissolved material or materials(individually or as a total) other than the identified materials.

As used herein, “fluoride compound” corresponds to species includingionic fluoride ion (F-) or covalently bonded fluorine. It is to beappreciated that the fluoride species may be included as a fluoridespecies or generated in situ. In certain embodiments, this compoundcapable of generating ions or the fluoride ion will be derived from HFor moonoflurophosphoric acid. In concentrated phosphoric acidcompositions, HF will exist mostly in the form of monofluorophosphoricacid (MFPA). In certain embodiments, the non-volatile MFPA may be useddirectly in the compositions in order to simplify addition and blending.In other embodiments, the fluoride compound may be chosen from CsF andKF. In other embodiments, the fluoride compound may be chosen fromtetramethylammonium hexafluorophosphate; ammonium fluoride; ammoniumbifluoride; quaternary ammonium tetrafluoroborates and quaternaryphosphonium tetrafluoroborates having the formula NR′₄BF₄ and PR′₄BF₄,respectively, wherein each R′ may be the same as or different from oneanother and is chosen from hydrogen, straight-chained, branched, orcyclic C₁-C₆ alkyl (e.g., methyl, ethyl, propyl, butyl, pentyl, hexyl),and straight-chained or branched C₆-C₁₀ aryl (e.g., benzyl);tetrabutylammonium tetrafluoroborate (TBA-BF₄); and combinationsthereof. In certain embodiments, the fluoride compound is selected fromammonium fluoride, ammonium bifluoride, quaternary ammoniumtetrafluoroborates (e.g., tetramethylammonium tetrafluoroborate,tetraethylammonium tetrafluoroborate, tetrapropylammoniumtetrafluoroborate, tetrabutylammonium tetrafluoroborate), quaternaryphosphonium tetrafluoroborates, or combinations thereof. In certainembodiments, the fluoride compound comprises ammonium bifluoride,ammonium fluoride, or a combination thereof.

As used in the specification and the appended claims, the singular forms“a,” “an” and “the” include their plural referents unless the contextclearly dictates otherwise. The terms “containing” or “including” areintended to be synonymous with the term “comprising”, meaning that atleast the named compound, element, particle, or method step, etc., ispresent in the composition or article or method, but does not excludethe presence of other compounds, materials, particles, method steps,etc., even if the other such compounds, material, particles, methodsteps, etc., have the same function as what is named, unless expresslyexcluded in the claims.

In certain embodiments, the term “alkyl” refers to a straight orbranched chain alkyl group having from one to twelve carbon atoms andthe term “alkenyl” refers to a straight or branched chain hydrocarbongroup having at least one carbon-carbon double bond and from two totwelve carbon atoms.

In one aspect, the invention provides a composition comprising thereaction product of

(A) at least one compound selected from:

tetraalkyldisiloxane-silyldiamines;

linear and cyclic alkylsilazanes,

1,3 bis(n-aminoalkylaminoalkyl) tetraalkylsiloxanes,

1,3 bis(n-aminoalkyl) tetraalkylsiloxanes,

alkyl, aryl, alkenyl, heteroalkyl/aryl boronic acids,

tungstosilicic acid,

phosphotungstic acid,

poly(vinyl alcohol),

poly(vinylpyrrolidone),

O-phosphorylethanolamine,

phosphorylcholine,

phosphatidylserine

trialkylsilylamines,

trialkylsilylurea, and

trialkylsilylcarbamates.

(B) phosphoric acid; and

(C) a solvent comprising water.

As used above, the phrase “reaction product of . . . ” reflects thecircumstances where the starting compounds recited in component (A)hydrolyze to yield other species.

In certain embodiments, the tetraalkyldisiloxane-silyldiamines arecompounds having the Formula (I)

wherein each R¹ and each 2 is independently chosen from C₁-C₆ alkylgroups.

In certain embodiments, the alkylsilazanes are compounds having theFormula (II)

wherein R³ is C₁-C₆ alkyl, R⁴ is C₂-C₆ alkenyl, and R is aryl.

In certain embodiments, the alkylcyclosilazanes are compounds of theFormula (III) and Formula (IV):

wherein each R⁶ is independently chosen from C₁-C₆ alkyl.

In certain embodiments, the polysilazanes are compounds having theFormula (V):

wherein R⁷ is hydrogen or C₁-C₆ alkyl, R⁸ is C₁-C₆ alkyl or aryl, and nis an integer from 10 to about 100.

In certain embodiments, the 1,3 bis(n-aminoalkyaminoalkyl)tetraalkylsiloxanes are compounds of the Formula (VI):

wherein each n is independently 1, 2, 3, or 4. An example of such acompound is 1,3-bis(2-aminoethylaminomethyl)tetramethyldisiloxane.

In certain embodiments, the 1,3-bis(n-aminoalkyl)tetraalkylsiloxane is a1,3-bis(n-aminoalkyl)tetramethylsiloxane compound of the Formula (VII):

wherein each n is independently 1, 2, 3, or 4. An example of such acompound is 1,3 bis(3-aminopropyltetramethyldisiloxane).

Tetraalkoxy dimethyl-disiloxanes are compounds of the Formula (VIII):

wherein R⁹ is C₁-C₆ alkyl, R¹⁰ is C₁-C₆ alkyl or aryl, and R¹¹ is C₁-C₆alkyl or C₂-C₈ alkenyl.

In certain embodiments, the alkyl, aryl, alkenyl, heteroalkyl/arylboronic acids are compounds of the Formula (IX)

wherein R¹² is chosen from C₁-C₆ alkyl, C₂-C₈ alkenyl, aryl, andheteroaryl.

As used herein, the term “tungstosilicic acid” as referred to herein isused in the form of a hydrate and is commercially available.Tungstosilicic acid has the general formula H₄[Si(W₃O₁₀)₄].xH₂O (CAS No.12027-43-9).

As used herein, the term “Phosphotungstic acid” as referred to herein isused in the form of a hydrate and is commercially available.Phosphotungstic acid has the general formula H₃[P(W₃O₁₀)₄].xH₂O (CAS No.12501-23-4).

As used herein, “O-phosphorylethanolamine” is used in the form of awater-soluble white powder and is commercially available fromSigma-Aldrich (CAS Number: 1071-23-4).

As used herein, “phosphorylcholine”, also known as2-(trimethylazaniumyl)ethyl hydrogen phosphate, is commerciallyavailable from Ambinter SARL. (CAS No. 107-73-3).

As used herein, “phosphatidylserine” is commercially available fromnumerous sources (CAS No. 51446-62-9).

As used herein, the term “poly(vinyl alcohol)” refers to partiallyhydrolyzed poly(vinyl alcohol) which has better solubility in aqueousenvironments and is commercially available from Sigma-Aldrich; thepolyvinyl alcohol has a weight average molecular weight (M_(w)) of about5000 to about 100,000. (CAS No. 25213-24-5).

As used herein, the term “poly(vinylpyrrolidone)” refers to commerciallyavailable materials available from Sigma-Aldrich. In certainembodiments, the poly(vinylpyrrolidone) has a weight average molecularweight (M_(w)) of about 5000 to about 100,000. (CAS No. 9003-39-8)

As used herein, the term “trialkylsilylamines” refers to compoundshaving the formula (R¹³)₃Si—O—R¹⁴, wherein each R¹³ group isindependently a C₁-C₆ alkyl group and R¹⁴ is hydrogen or a metal cation,such as K⁺, Na⁺, Ca⁺, or Li⁺.

As used herein, the term “trialkysilylamines” refers to compounds havingat least one silyl group, at least one amino group, either of which maybe substituted by one or more C₁-C₆ alkyl groups. Example includeN-(trimethylsilyl)diethylamine, N-(triethylsilyl)diethylamine,N-(trimethylsilyl)-di-N-propylamine, N-(trimethylsilyl)dibutylamineN-(trimethylsilyl)dipentylamine N-(trimethylsilyl)dihexylamine, and thelike.

As used herein, the term “trialkylsilylurea” refers to compounds havinga urea moiety, i.e., a partial structure:

substituted by one or more trialkylsilyl groups or trialkylsilylaminogroups. An example of such a compound is 1,3-Bis(trimethylsilyl)urea,commercially available from Sigma-Aldrich (CAS No. 18297-63-7).

The term “trialkylsilylcarbamates” refers to compounds having acarbamate moiety, i.e., a partial structure:

substituted by one or more C₁-C₆ alkyl groups and at least one C₁-C₆trialkylsilyl groups. An example of such a compound isN,O-(trimethylsilyl)carbamate, available from Sigma-Aldrich (CAS No.35342-88-2).

As used herein, the term “C₁-C₆ alkyl” refers to straight orbranched-chain saturated hydrocarbon groups, containing from one to sixcarbon atoms. Included are groups such as methyl, ethyl, n-propyl,isopropyl, n-butyl, isobutyl, t-butyl, n-pentyl, isopentyl, amyl,n-hexyl, and isohexyl.

As used herein the term “C₂-C₈ alkenyl” refers to a straight or branchedchain hydrocarbon radical that contains at least one carbon-carbondouble bond and three to eight carbon atoms.

As used herein, “aryl” includes phenyl and napthyl and such groupssubstituted with one to three groups chosen from C₁-C₆ alkyl, C₁-C₆alkoxy, —CN, —NO₂, C₁-C₆ alkoxycarbonyl, C₁-C₆ alkanoyloxy, C₁-C₆alkylsulfonyl, hydroxyl, carboxyl, and halogen.

The term “heteroaryl” includes 5 or 6-membered heterocyclic aryl ringscontaining one oxygen atom, and/or one sulfur atom, and up to threenitrogen atoms, said heterocyclic aryl ring optionally fused to one ortwo phenyl rings. Examples of such systems include thienyl, furyl,pyrrolyl, imidazolyl, pyrazolyl, thiazolyl, isothiazolyl, oxazolyl,isoxazolyl, triazolyl, thiadiazolyl, oxadiazolyl, tetrazolyl,thiatriazolyl, oxatriazolyl, pyridyl, pyrimidyl, pyrazinyl, pyridazinyl,thiazinyl, oxazinyl, triazinyl, thiadiazinyl, oxadiazinyl, dithiazinyl,dioxazinyl, oxathiazinyl, tetrazinyl, thiatriazinyl, oxatriazinyl,dithiadiazinyl, imidazolinyl, dihydropyrimidyl, tetrahydropyrimidyl,tetrazolo-[1,5-b]pyridazinyl and purinyl, benzoxazolyl, benzothiazolyl,benzimidazolyl, indolyl and the like; such groups are optionallysubstituted with one to three groups selected from C₁-C₆-alkyl,C₁-C₆-alkoxy, —CN, —NO₂, C₁-C₆-alkoxycarbonyl, C₁-C₆-alkanoyloxy,C₁-C₆-alkylsulfonyl, and halogen groups.

Many of the compounds of component A tend to hydrolyze to other speciesin the presence of aqueous phosphoric acid under the conditionstypically utilized in a silicon nitride etching method. Several mono-and difunctional silylphosphates formed upon acid hydrolysis willcondense with the oxide surface silanol species, inhibiting furtheretch/dissolution and silicic acid oligomers redeposition during etch.

In one embodiment, the compound of Formula (I) isN¹,N¹,N³,N³-tetraethyl-1,1,3,3-tetramethyl-1,3-Disiloxanediamine.Compounds of Formula (I) can also be used in combination with atetraalkoxy dimethyl-disiloxane of Formula (VIII), such as1,1,3,3-tetramethoxy-1,3-dimethyl. The compound of Formula (I) was foundto hydrolyze in the presence of aqueous phosphoric acid to componentcompounds which served to passivate the silicon dioxide surfaces andthus inhibit the undesired etching of the silicon dioxide surface infavor of the desired etching of the silicon nitride surfaces:

Protonated diethylamine formed during silazane Si—N bond breaking canserve as silicic acid oligomers solubilizer, thus increasing theconcentration of soluble silicate species and substantially reducing theundesired silicate redeposition on the oxide features (see for example,FIG. 1D of US 2017/0287725).

In certain embodiments, the phosphoric acid will be present in thecomposition in about 50 to about 95 weight percent. In otherembodiments, phosphoric acid will be present in about 70 to about 90weight percent, and in other embodiments, about 85 weight percent.

In certain embodiments of the invention, the composition may furthercomprise a fluoride compound. In one embodiment, the fluoride compoundis selected from HF and monofluoro phosphoric acid. In otherembodiments, the fluoride compound is selected from cesium fluoride andpotassium fluoride. In other embodiments, the fluoride compound isselected from from fluoroboric acid; tetramethylammoniumhexafluorophosphate; ammonium fluoride; ammonium bifluoride; quaternaryammonium tetrafluoroborates and quaternary phosphoniumtetrafluoroborates having the formula NR′₄BF₄ and PR′₄BF₄, respectively,wherein R′ may be the same as or different from one another and isselected from hydrogen, straight-chained, branched, or cyclic C₁-C₆alkyl, and straight-chained or branched C₆-C₁₀ aryl; tetrabutylammoniumtetrafluoroborate (TBA-BF₄); and combinations thereof.

Component (c) is a solvent comprising water. Optionally, the solvent mayfurther comprise one or more water-miscible solvents such aspyrrolidinones, glycols, amines, and glycol ethers, including, but notlimited to, methanol, ethanol, isopropanol, butanol, and higher alcohols(such as C₂-C₄ diols and C₂-C₄ triols), tetrahydrofurfuryl alcohol(THFA), halogenated alcohols (such as 3-chloro-1,2-propanediol,3-chloro-1-propanethiol, 1-chloro-2-propanol, 2-chloro-1-propanol,3-chloro-1-propanol, 3-bromo-1,2-propanediol, 1-bromo-2-propanol,3-bromo-1-propanol, 3-iodo-1-propanol, 4-chloro-1-butanol,2-chloroethanol), dichloromethane, chloroform, acetic acid, propionicacid, trifluoroacetic acid, tetrahydrofuran N-methylpyrrolidinone (NMP),cyclohexylpyrrolidinone, N-octylpyrrolidinone, N-phenylpyrrolidinone,methyldiethanolamine, methyl formate, dimethyl formamide (DMF),dimethylsulfoxide (DMSO), tetramethylene sulfone (sulfolane), diethylether, phenoxy-2-propanol (PPh), propriophenone, ethyl lactate, ethylacetate, ethyl benzoate, acetonitrile, acetone, ethylene glycol,propylene glycol (PG), 1,3-propanediol, dioxane, butyryl lactone,butylene carbonate, ethylene carbonate, propylene carbonate, dipropyleneglycol, diethylene glycol monomethyl ether, triethylene glycolmonomethyl ether, diethylene glycol monoethyl ether, triethylene glycolmonoethyl ether, ethylene glycol monopropyl ether, ethylene glycolmonobutyl ether, diethylene glycol monobutyl ether (i.e., butylcarbitol), triethylene glycol monobutyl ether, ethylene glycol monohexylether, diethylene glycol monohexyl ether, ethylene glycol phenyl ether,propylene glycol methyl ether, dipropylene glycol methyl ether (DPGME),tripropylene glycol methyl ether (TPGME), dipropylene glycol dimethylether, dipropylene glycol ethyl ether, propylene glycol n-propyl ether,dipropylene glycol n-propyl ether (DPGPE), tripropylene glycol n-propylether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether,tripropylene glycol n-butyl ether, propylene glycol phenyl ether,dipropylene glycol methyl ether acetate, tetraethylene glycol dimethylether (TEGDE), dibasic ester, glycerine carbonate, N-formyl morpholine,triethyl phosphate, and combinations thereof. When using an alkoxysilaneadditive, its hydrolysis generates a small amount of alcohol, forexample, methanol or ethanol, which is incorporated into the formulationas the alcohol itself or as its phosphoric acid monoester. In addition,the organic solvent may comprise other amphiphilic species, i.e.,species that contain both hydrophilic and hydrophobic moieties similarto surfactants.

In certain embodiments, the compositions of the invention furthercomprise low molecular weight amines and amine phosphate salts. In otherembodiments, the low molecular weight amines and amine phosphate saltsare primary, secondary, or tertiary C₁-C₆ alkylamine or phosphate saltsthereof. Examples include trimethylamine, trimethylamine,tripropylamine, tributylamine and the like. It will be appreciated thatwhen such amines are added to a concentrated H₃PO₄ composition, aminephosphate salts will form.

The composition may optionally comprise surfactant(s) (different fromthe other optional or required ingredients of the present description)to improve performance of the composition. As used herein the term“surfactant” refers to an organic compound that lowers the surfacetension (or interfacial tension) between two liquids or between a liquidand a solid, typically an organic amphiphilic compound that contains ahydrophobic group (e.g., a hydrocarbon (e.g., alkyl) “tail”) and ahydrophilic group. Preferred surfactants are thermally stable and stayionic under strongly acidic conditions such as the conditions of anetching process of the present invention. Examples includeperfluoroalkylsulfonic acids and long-chain quaternary ammoniumcompounds (e.g. dodecyltrimethylammonium hydrogen sulfate). Fluorinatednon-ionic surfactants such as Chemours' Capstone® FS-31/FS-35 can alsobe used. Non-ionic nonfluorinated surfactants such as poly(ethyleneglycol)-poly(propylene glycol) copolymers (“PEG-PPG”) can also be used,and are better suited for the lower-temperature, lower-acidity part ofthe operating range (e.g., 100-130° C. and 50-75% H₃PO₄).

The amount of surfactant in the composition can be an amount that, incombination with the other materials of an etching composition, willprovide desired overall performance. For example, the composition cancontain an amount of surfactant that may be in a range from about 0.001to about 10 weight percent, e.g., from about 0.01 to about 0.5, 1, 2, 7,or 7 weight percent surfactant based on total weight of the composition.

Optionally, the compositions can contain an amount of carboxylic acidcompound, meaning an organic compound that contains at least onecarboxylic acid group. According to the invention, the presence of acarboxylic acid compound in composition as described can improveperformance by inhibiting redeposition of silicon oxide or formation ofparticles of the same. In certain embodiments, the carboxylic acidcompounds for use in the compositions include acetic acid, malonic acid,succinic acid, 2-methylsuccinic acid, glutaric acid, adipic acid,salicylic acid, 1,2,3-propanetricarboxylic acid (a.k.a. tricarballylicacid), 2-phosphonoacetic acid, 3-phosphonopropanoic acid, and2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA), any of which may beused alone, in combination together with each other, or in combinationwith a different carboxylic acid compound.

The amount of carboxylic acid compound (including derivatives thereof)contained in the compositions can be an amount that, in combination withthe other materials of the compositions, will provide desired etchingperformance while not otherwise affecting performance or chemicalstability of an etching composition. For example, the compositions cancontain an amount of carboxylic acid compound, which may be a singlespecies or a combination of two or more species, in a range from about0.01 to about 10 weight percent based on total weight of thecomposition, or from about 0.1 to about 5 or 8 weight percent based ontotal weight of the composition.

The composition may contain water from one or from multiple sources. Forexample, water will be present in an aqueous phosphoric acid ingredient.Additionally, water may be used as a carrier for one or more of theother ingredients of the etching composition, and water may be addedalone as its own ingredient. The amount of water should be sufficientlylow to allow the composition to exhibit desired or preferred oradvantageous etching performance properties, including a useful(sufficiently high) silicon nitride etch rate. An increase in thepresence of water tends to increase the etch rate of silicon nitride butcan also depress the boiling point of the etching composition, whichforces a reduction in operating temperature of the etching compositionand an opposite effect. Examples of amounts of water, from all sources,in an etching composition, can be less than about 50, 40, or 30 weightpercent, for example in a range from about 5 weight percent to about 25percent by weight, based on total weight of the composition, or in arange from about 10 to 20 weight percent water based on total weight ofthe composition.

Optionally, these and other example compositions as described cancontain, consist of, or consist essentially of the phosphoric acid, thecomponent A materials, and any one or any combination of the identifiedoptional ingredients. Certain embodiments of the compositions of theinvention do not require and may exclude other types of ingredients nottypically included in an etching composition, such as a pH adjustingagent (other than the acids mentioned as potential ingredients herein)and solid materials such as abrasive particles.

In yet another aspect, the invention provides a method for removingsilicon nitride from a microelectronic device, said method comprisingcontacting the microelectronic device with a composition of the presentinvention, for sufficient time under sufficient conditions to at leastpartially remove said silicon nitride material from the microelectronicdevice.

For example, silicon nitride material may be removed withoutsubstantially damaging metal and metal silicide interconnect materials.The invention thus provides methods for selectively and substantiallyremoving silicon nitride materials relative to polysilicon and/orsilicon oxide materials from the surface of the microelectronic devicehaving same thereon using the compositions described herein. The metalsilicide materials that are present are not substantially corroded bysaid removal compositions using said method.

In etching application, the composition is applied in any suitablemanner to the surface of the microelectronic device having the siliconnitride material thereon, e.g., by spraying the removal composition onthe surface of the device, by dipping (in a static or dynamic volume ofthe removal composition) of the device including the silicon nitridematerial, by contacting the device with another material, e.g., a pad,or fibrous sorbent applicator element, that has the removal compositionabsorbed thereon, by contacting the device including the silicon nitridematerial with a circulating removal composition, or by any othersuitable means, manner or technique, by which the removal composition isbrought into removal contact with the silicon nitride material. Theapplication may be in a batch or single wafer apparatus, for dynamic orstatic cleaning. In one embodiment, the application of the removalcomposition to the surface of the microelectronic device is controlledagitation whereby the composition is circulated through the containerhousing said composition. Active agitation, e.g., turbulence, stirring,etc., is not recommended when the etch rates of silicide and/or poly-Siare preferably low. However, for removal of silicon nitride from highaspect ratio structures, stirring may be desired, both for faster liquidexchange in and out of the structure and to minimize redeposition ofoxide.

The compositions of the present invention, by virtue of theirselectivity for silicon nitride material relative to other materialsthat may be present on the microelectronic device structure and exposedto the composition, such as metallization, polysilicon, siliconoxide(s), etc., achieve at least partial removal of the silicon nitridematerial in a highly efficient and highly selective manner.

In use of the compositions of the invention for removing silicon nitridematerial from microelectronic device structures having same thereon, thecomposition typically is contacted with the microelectronic devicestructure for a sufficient time of from about 1 minute to about 200minutes, in one embodiment, about 15 minutes to about 100 minutes, orabout 1 minute to about 2 minutes for a single wafer tool, at sufficientconditions including, but not limited to, in one embodiment, atemperature in a range of from about 40° C. to about 120° C., or inanother embodiment, about 60° C. to about 95° C. Such contacting timesand temperatures are illustrative, and any other suitable time andtemperature conditions may be employed that are efficacious to at leastpartially remove the silicon nitride material from the device structure,within the practice of the invention.

Following the achievement of the desired removal action, the removalcomposition is readily removed from the microelectronic device to whichit has previously been applied, e.g., by rinse, wash, or other removalstep(s), as may be desired and efficacious in a given end useapplication of the compositions of the present invention. For example,the device may be rinsed with a rinse solution including deionized waterand/or dried (e.g., spin-dry, N₂, vapor-dry, etc.).

The compositions of the invention selectively etch silicon nitridematerial relative to poly-Si and silicon oxides from the surface of themicroelectronic device without causing substantial corrosion of themetal and/or metal silicide interconnect material(s). For example, theselectivity of silicon nitride to silicon oxide(s) in the presence ofthe removal compositions of the invention are, in one embodiment, in arange from about 10:1 to about 7,000:1, in another embodiment about 30:1to about 3,000:1, and in another embodiment about 100:1 to about 2000:1at temperatures of 40-100° C. in one embodiment, of 60-95° C. in anotherembodiment, and of 75-90° C. in yet another embodiment. When the silicicacid source includes an alkoxysilane, e.g., TEOS, the selectivity ofsilicon nitride relative to silicon oxide(s) can be tuned from about20:1 to infinity in one embodiment and in the range from about 20:1 toabout 7,000:1 in another embodiment. In fact, the selectivity isformally negative for fluorosilicic acid/TEOS molar ratios below about4, reflecting the fact that the thickness of the oxide film is slightlybut measurably increased by precipitation of silica. When the silicicacid source includes fine silica powder, the observed selectivity ofsilicon nitride relative to silicon oxide(s) is in the range of about20:1 to about 100:1 but higher selectivity may be obtained by longerequilibration times (or higher equilibration temperature) of the silicapowder with the fluorosilicic acid.

An etching step of the present description can be useful to etch siliconnitride material from a surface of any type of substrate. According toparticular embodiments, a substrate can include alternating thin filmlayers of silicon nitride as structural features of a substrate thatincludes alternating thin film layers of the silicon nitride layers withsilicon oxide. The silicon oxide layers are high aspect ratio structuresthat contain the silicon nitride layers disposed between the layers ofsilicon oxide.

A still further aspect of the invention relates to methods ofmanufacturing an article comprising a microelectronic device, saidmethod comprising contacting the microelectronic device with thecompositions of the present invention for sufficient time to etchinglyremove silicon nitride material from the surface of the microelectronicdevice having same thereon, and incorporating said microelectronicdevice into said article.

The compositions described herein are easily formulated by simpleaddition of the respective ingredients and mixing to homogeneouscondition. Furthermore, the compositions may be readily formulated assingle-package formulations or multi-part formulations that are mixed atthe point of use. The individual parts of the multi-part formulation maybe mixed at the tool or in a storage tank upstream of the tool. Theconcentrations of the respective ingredients may be widely varied inspecific multiples of the composition, i.e., more dilute or moreconcentrated, and it will be appreciated that the compositions describedherein can variously and alternatively comprise, consist or consistessentially of any combination of ingredients consistent with thedisclosure herein.

Another aspect of the invention relates to a kit including, in one ormore containers, one or more components adapted to form the compositionsdescribed herein. In one embodiment, the kit includes, in one or morecontainers, the combination of at least one of components (A)-(C) abovefor combining with water at the fab or the point of use. The containersof the kit must be suitable for storing and shipping said cleaningcomposition components, for example, NOWPak®. containers (Entegris,Inc., Danbury, Conn., USA). The one or more containers which contain thecomponents of the first cleaning composition preferably include meansfor bringing the components in said one or more containers in fluidcommunication for blending and dispense. For example, referring to theNOWPak®. containers, gas pressure may be applied to the outside of aliner in said one or more containers to cause at least a portion of thecontents of the liner to be discharged and hence enable fluidcommunication for blending and dispense. Alternatively, gas pressure maybe applied to the head space of a conventional pressurizable containeror a pump may be used to enable fluid communication. In addition, thesystem preferably includes a dispensing port for dispensing the blendedcleaning composition to a process tool.

Substantially chemically inert, impurity-free, flexible and resilientpolymeric film materials, such as high density polyethylene, may be usedto fabricate the liners for said one or more containers. Desirable linermaterials are processed without requiring co-extrusion or barrierlayers, and without any pigments, UV inhibitors, or processing agentsthat may adversely affect the purity requirements for components to bedisposed in the liner. A listing of desirable liner materials includefilms comprising virgin (additive-free) polyethylene, virginpolytetrafluoroethylene (PTFE), polypropylene, polyurethane,polyvinylidene chloride, polyvinylchloride, polyacetal, polystyrene,polyacrylonitrile, polybutylene, and so on. Exemplary thicknesses ofsuch liner materials are in a range from about 5 mils (0.005 inch) toabout 30 mils (0.030 inch), as for example a thickness of 20 mils (0.020inch).

Regarding the containers for the kits, the disclosures of the followingpatents and patent applications are hereby incorporated herein byreference in their respective entireties: U.S. Pat. No. 7,188,644entitled “APPARATUS AND METHOD FOR MINIMIZING THE GENERATION OFPARTICLES IN ULTRAPURE LIQUIDS;” U.S. Pat. No. 6,698,619 entitled“RETURNABLE AND REUSABLE, BAG-IN-DRUM FLUID STORAGE AND DISPENSINGCONTAINER SYSTEM;” and U.S. Patent Application No. 60/916,966 entitled“SYSTEMS AND METHODS FOR MATERIAL BLENDING AND DISTRIBUTION” filed onMay 9, 2007 in the name of John E. Q. Hughes, and PCT/US08/63276entitled “SYSTEMS AND METHODS FOR MATERIAL BLENDING AND DISTRIBUTION”filed on May 9, 2008 in the name of Advanced Technology Materials, Inc.

Accordingly, in a further aspect, the invention provides a kitcomprising one or more containers having components therein suitable forremoving silicon nitride from a microelectronic device, wherein one ormore containers of said kit contains components A, B, and C as set forthherein.

This invention can be further illustrated by the following examples ofpreferred embodiments thereof, although it will be understood that theseexamples are included merely for purposes of illustration and are notintended to limit the scope of the invention unless otherwisespecifically indicated.

Experimental Section

SiO₂* ER Si₃N₄* ER SiO₂** ER Si₃N₄** ER Ex. # SiO₂ Inhibitor A/min A/minSelectivity* A/min A/min Selectivity** Ctrl 1 None 0.6823 33.9 49.730.11 72.3 657 Ctrll 2 APST 0.5261 38.8 73.75 0.04 150 3750 1 NTTDSDA0.2869 27 94.02 0.01 145.8 1458 2 HMCTSZ 0.2542 25.2 99.23 3 AEAMTMD0.2576 29.4 114.25 0.06 170 2724.5 4 NTTDSDA 0.315 32 101.6 5 NTTDSDA +0.001 31.4 31400 0.06 145.2 2231.046 Disiloxane (0.001 moles) 6NTTDSDA + 0.001 46.1 46100 0.02 148.4 7420 disiloxane (0.002 moles) 7PyBA 0.465 25.4 84.53 8 PhBA 0.37 29.7 80.23 9 O-PPEA 0.2 34.9 164.1 0.2210.7 1050 In the table above: NTTDSDA =N¹,N¹,N³,N³-tetraethyl-1,1,3,3-tetramethyl-1,3-disiloxanediamine APST =(3-aminopropyl)silane triol (CAS No. 58160-99-9) HMCTSZ =2,2,4,4,6,6-hexamethylcyclotrisilazane AEAMTMD =1,3-bis(2-aminoethylaminomethyl)tetramethyldisiloxane disiloxane =1,1,3,3-tetramethoxy-1,3-tetramethyl disiloxane PyBA = 4-pyridylboronicacid PhBA = phenylboronic acid O-PPEA = O-phosphorylethanolamine (Si₃N₄etch accelerator) *SiO₂, Si₃N₄ films - deposition technique A **SiO₂,Si₃N₄ films - deposition technique B

Selectivity is variable depending on the SiO₂ and Si₃N₄ depositiontechniques (precursors, ratios, temperature, etc.), resulting indifferent surface chemistry of the oxide and nitride films (functionalgroups, condensation degree). For instance, SiO₂ films with highersurface silanol condensation, less free silanol (—Si—OH) groups and moresurface siloxane (—O—Si—O—) groups will etch slower, while Si₃N₄ filmswith higher primary and secondary amine groups concentration and lesstertiary amines surface and bulk concentration will etch faster.

FIG. 1 shows the selectivity variation for two etch formulations ondifferent types of oxide and nitride substrates with different surfacechemistry, made by different deposition techniques:

The invention has been described in detail with particular reference tocertain embodiments thereof, but it will be understood that variationsand modifications can be affected within the spirit and scope of theinvention.

The invention claimed is:
 1. A composition comprising the reactionproduct of: (A) at least one compound selected from:tetraalkyldisiloxane-silyldiamines and 1,3bis(n-aminoalkylaminoalkyl)tetraalkylsiloxanes; (B) phosphoric acid; and(C) a solvent comprising water, wherein composition is an etchingcomposition for selectively etching silicon nitride, wherein thetetraalkyldisiloxane-silyldiamines are compounds having the formula:

wherein each R¹ and each R² is independently chosen from C₁-C₆ alkylgroups, and wherein the 1,3 bis(n-aminoalkylaminoalkyl)tetraalkylsiloxanes are compounds having the formula:

wherein each n is independently 1, 2, 3, or
 4. 2. The composition ofclaim 1, further comprising a fluoride compound.
 3. The composition ofclaim 2, wherein the fluoride compound is chosen from HF andmonofluorphosphoric acid.
 4. The composition of claim 2, wherein thefluoride compound is chosen from fluoroboric acid; tetramethylammoniumhexafluorophosphate; ammonium fluoride; ammonium bifluoride; quaternaryammonium tetrafluoroborates and quaternary phosphoniumtetrafluoroborates having the formula NR′₄BF₄ and PR′₄BF₄, respectively,wherein R′ may be the same as or different from one another and isselected from hydrogen, straight-chained, branched, or cyclic C₁-C₆alkyl, and straight-chained or branched C₆-C₁₀ aryl; and combinationsthereof.
 5. The compound of claim 2, wherein the fluoride compound ischosen from cesium fluoride and potassium fluoride.
 6. The compositionof claim 1, further comprising a primary, secondary, or tertiary C₁-C₆alkylamine, C₁-C₆ alkanolamine, or dihydrogen phosphate salt thereof. 7.The composition of claim 6, wherein the primary, secondary, or tertiaryC₁-C₆ alkylamine or C₁-C₆ alkanolamine is chosen from trimethylamine ortriethanolamine.
 8. The composition of claim 1, wherein thetetraalkyldisiloxane- silyldiamine is N¹,N¹,N³,N³-tetraethyl-1,1,3,3-tetramethyl- 1,3-disiloxanediamine.
 9. The composition of claim1, wherein the 1,3 bis(n-aminoalkylaminoalkyl) tetraalkylsiloxane is1,3-bis(2-aminoethylaminomethyl)tetramethyldisiloxane.
 10. Thecomposition of claim 1 further comprising an additional compound of theformula:

wherein R⁹ is C₁-C₆ alkyl, R¹⁰ is C₁-C₆ alkyl or aryl, and R¹¹ is C₁-C₆alkyl or C₂-C₈ alkenyl.
 11. The composition of claim 10, wherein theadditional compound is 1,1,3,3-tetramethoxy-1,3-dimethyldisiloxane. 12.A method for removing silicon nitride from a microelectronic device,said method comprising contacting the microelectronic device with acomposition comprising the reaction product of: (A) at least onecompound selected from: tetraalkyldisiloxane-silyldiamines and 1,3bis(n-aminoalkylaminoalkyl) tetraalkylsiloxanes; (B) phosphoric acid;and (C) a solvent comprising water, wherein composition is an etchingcomposition for selectively etching silicon nitride, wherein thetetraalkyldisiloxane-silyldiamines are compounds having the formula:

wherein each R¹ and each R² is independently chosen from C₁-C₆ alkylgroups, and wherein the 1,3 bis(n-aminoalkylaminoalkyl)tetraalkylsiloxanes are compounds having the formula:

wherein each n is independently 1, 2, 3, or 4.